1. Field of the Invention
The present invention relates to the preparation of a patch image.
2. Related Background Art
The color DTP is recently becoming popular with a computer system, as a result of recent advances in the color reproducing ability of the computer and in the performance of the color printers. In such field there are employed a calibration technology for the color printer for the purpose of realizing exact color reproduction and the preparation of a printer model for the color printer for the purpose of realizing more exact color matching, but either technology involves such steps as preparation of a patch image, output of the prepared patch image and measurement of the outputted patch image. However, exact measurement of the patch image is impossible because a noise is always involved in the output of the patch image. Therefore, assuming that the noise is white noise, the influence of noise is relaxed by outputting and measuring the same patch image plural times. Otherwise the influence of the noise is relaxed by outputting the patch image with a rotation process plural times and measuring such patch image.
It is however not reasonable to assume that the noise color signal (hereinafter called noise) mixed in the patch image is white noise, since such noise is strongly correlated with the color of the patch. Consequently, the relaxation of the influence of noise is inevitably limited even if the same image is outputted many times. It is therefore necessary to prepare a patch image in consideration of the correlation of the noise. Also in consideration of the convenience in practical use, the number of the patch images should be as small as possible. There is thus required a patch image preparing method capable of relaxing the influence of noise taking the correlation of the noise into consideration and utilizing the patch images of a number as small as possible.